https://www.advancedcustomfields.com/resources/query-posts-custom-fields/ see the section on querying on array based values. Also see this guide https://www.advancedcustomfields.com/resources/querying-relationship-fields/
$args = array(
...
'meta_query' => array(
array(
'key' => '',
'value' => '"'.$idArtist.'"',
'compare' => 'LIKE'
)
)
);
See https://developer.wordpress.org/reference/classes/wp_query/ for more info on properly constructing queries.