relation OR instead of AND – Filtered term ID’s in loop

Per the Codex:

relation (string) – The logical relationship between each inner
taxonomy array when there is more than one. Possible values are ‘AND’,
‘OR’. Do not use with a single inner taxonomy array.

So you are on the right track, but your tax_query is wrong. relation is part of the outer tax_query array and not part of the top level query arguments.

$query_args['tax_query'] = array(
  'relation' => 'OR', 
  array(
    'taxonomy' => $post_type . '_filters',
    'terms'    => $terms,
    'field'    => 'id', 
  )
);