The 19-year-old moved to Glasgow a year ago and has played in more than 40 games for the Scottish champions.
His 18-month deal ends in the summer and Roberts intends to return to City to battle for a place.
"I'll always have that belief; the more you play, the more you improve," said Roberts.
"It's been my first proper season playing men's football. I did a bit at Fulham, but I was in and out, the same at Man City, so coming here, the manager before [Ronny Deila] played me a lot and Brendan's [Rodgers] been really good with me as well.
"It's been good and I'm thoroughly enjoying it.  I came here to improve, to win trophies and score goals.
"Hopefully at the end of the season I can take that back with me to City and have a good go there. It's been a great experience and I'm thankful for that."
Roberts has often found Scott Sinclair and James Forrest starting games ahead of him this season, but the winger says he has learned from working alongside Sinclair in particular.
He also insists that the camaraderie within the squad has been a significant factor as Celtic reached the Champions League group stages and have put together a run of 25 unbeaten domestic matches.
If Celtic can avoid defeat against St Johnstone on Wednesday, they will equal the record of 26 set by the Lisbon Lions in the 1966-67 season. Roberts, though, insists that the players are not giving too much thought to the record.
"The team spirit's been great since day one, when the manager came in and the boys came back for pre-season," he said.
"We've kept each other going, we've had good times, fun together, and done well on the pitch. It shows in results and if we continue to do that, it should be a very good season for us.
"It's [about] momentum, you feel good, positive and go into every game believing you can win. The more you win, the more positive you are. We're in good stead right now and we'll go into Wednesday firing and ready to go.
"We're just going out with the mentality to win every game. On Wednesday we'll show that again. We'll be buzzing to be back in the league and looking to put on a good show.
"It's more other people [looking at the record], we just focus on trying to win. We'll do all we can to do that and focus on the game."

Larger firms - defined as those with over 100 staff - were more likely to be attacked than smaller counterparts, said the British Chambers of Commerce (BCC), which surveyed 1,200 companies.
Its report found 42% of larger firms had been the victim of a cyber attack, compared with 18% of smaller ones.
The business group has urged companies to do more to protect themselves.
Just a quarter of the firms the BCC surveyed said they had put in place security measures to protect themselves against hacking.
"Cyber attacks risk companies' finances, confidence and reputation, with victims reporting not only monetary losses, but costs from disruption to their business and productivity.
"Firms need to be proactive about protecting themselves from cyber attacks," said BCC director-general Adam Marshall.
Household names including Yahoo, eBay and TalkTalk have all fallen victim to major cyber attacks.
Last year, Tesco Bank reported losing Â£2.5m in an unprecedented breach at a British bank.
The law requires organisations to have appropriate measures in place to keep people's personal data secure.
Next year data protection regulation will be extended, increasing businesses' responsibilities to protect personal data.
"Firms that don't adopt the appropriate protections leave themselves open to tough penalties," warned Mr Marshall.

David Skeen, 51, was last seen going for a run in Talgarth, near Brecon, at 09:00 GMT on Tuesday.
Firefighters, police and more than 45 mountain rescue volunteers had been out searching for Mr Skeen. A drone was used during the day.
Mr Skeen was last seen wearing an orange gilet, black running trousers, pale trainers and a blue hat.
Dyfed-Powys Police said they would continue to follow up any lines of inquiry overnight.
Patrick Roberts believes his loan spell at Celtic will prepare him for the challenge of trying to break into the Manchester City first team.
[NEXT_CONCEPT]
One in five British firms was hit by a cyber attack last year, research suggests.
[NEXT_CONCEPT]
The search for a jogger who has been missing for more than 24 hours in Powys has been stood down for the night.