code: public function update($partialDocument, $id, array $options = array()) {
          $document = json_encode(array('doc' => $partialDocument));
          $url = $this->buildUrl(array($this->type, $id));
          $response = $this->conn->set($url, $document);
  
          return array(
              'ok' => $response,
          );
      }
docs: Update a part of a document
  
  @return array
  @param  array                    $partialDocument
  @param  mixed                    $id
  @param  array                    $options