code: public function searchConfig($query)
      {
          $configArray = array();
  
          $configArray = Mage::helper('sheep_debug')->xml2array($this->getConfig()->getNode(), $configArray);
  
          $results = array();
          $configKeys = array_keys($configArray);
          foreach ($configKeys as $configKey) {
              if (strpos($configKey, $query) !== FALSE) {
                  $results[$configKey] = $configArray[$configKey];
              }
          }
  
          return $results;
      }
docs: Searches configuration keys
  
  @param string $query
  @return array