Return multiple comment_meta keys

I've this code

$args = array(
                'post_id' => $post_id,
                'meta_query' => array(
                                        'relation' => 'AND',
                                        array(
                                            'key' => 'review_title'
                                        ),
                                        array(
                                            'key' => 'review_rating',
                                        )
                                    ),
            );

$comments_query = new WP_Comment_Query;   
$comments_array = $comments_query->query( $args );

It works fine, will work only if review_title AND review_rating exists. But it return only the second key, and I need to return both