code: public function update($partialDocument, $id, $index, $type, array $options = array()) {
          $params = array(
              '_id'    => $id,
              '_index' => $index,
              '_type'  => $type,
          );
  
          foreach ($options as $key => $value) {
              $params['_'.$key] = $value;
          }
  
          $operation = array(
              array('update' => $params),
              array('doc'    => $partialDocument),
          );
          $this->operations[] = $operation;
  
          return $this;
      }
docs: Update a part of a document
  
  @param array  $partialDocument
  @param mixed  $id
  @param string $index    Index
  @param string $type     Type
  @param array  $options  Allow sending query parameters to control indexing further
  _refresh_ *bool* If set to true, immediately refresh the shard after indexing
  
  @return \Elasticsearch\Bulk