我想知道这是否适用于您：

function search_filter( $query )
{
    if( $query->is_search AND $query->is_main_query() )
    {
        // $query->set( \'post_parent__not_in\', array( 0 ) ); // We comment this out here 
        $query->set( \'post_type\', array( \'post\', \'page\' ) );
    }
    return $query;
}
add_action( \'pre_get_posts\', \'search_filter\' );

function wpse_120638( $where, $query ) 
{
    global $wpdb;

    if( $query->is_search AND $query->is_main_query() )
    {
            $from = "AND $wpdb->posts.post_type IN (\'post\', \'page\')";
            $to   = "AND ( ( $wpdb->posts.post_parent NOT IN (0) 
                     AND $wpdb->posts.post_type IN (\'page\') ) 
                     OR $wpdb->posts.post_type IN (\'post\') ) ";

        $where = str_replace( $from, $to, $where );                                   
    }

    return $where;
}
add_filter( \'posts_where\', \'wpse_120638\', 10, 2 );