facetwp meta query order by field

<?php

$args = array(
  'level' = > array(
    'key' => '_hmd_practice_membership_level',
    'value' => array( 'gold', 'silver', 'bronze', 'basic', 'free' ),
    'compare' => 'IN'
  )
);

$query->set( 'meta_query', $args );
$query->set( 'orderby', 'level' );
$query->set( 'order', FIELD('gold', 'silver', 'bronze', 'basic', 'free') );