Filter by custom fields

function filter_by_custom_fields( $query ) {
    $custom_fields = array(
        'frame_height',
        // ...
    );

    $meta_query = array();

    foreach ( $custom_fields as $field ) {
        if ( ! isset( $_GET[ $field ] ) ) {
            continue;
        }

        $meta_query[] = array(
            'key'     => $field,
            'value'   => sanitize_text_field( $_GET[ $field ] ),
            'compare' => 'LIKE',
        );
    }

    if ( $meta_query ) {
        $query->set( 'meta_query', $meta_query );
    }
}
add_action( 'pre_get_posts', 'filter_by_custom_fields' );