wp parse_query not working with custom meta value

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I ave faced the same issue when I was trying to filter custom-post-type with custom-field
but I have resolved this issue in the following steps.
Converted custom-field name from writer to _writer
and then I have updated following code inside callback function of parse_query hook that I can add custom-field meta_query like 

$query->set( 'meta_query', array(
    array(
          'key'     => '_writer',
           'compare' => '=',
           'value'   => $_GET['_writer'],
           'type'    => 'numeric',
      )
) );

This Above Solution Worked for me.
Documentation https://developer.wordpress.org/reference/hooks/pre_get_posts/
Helpful Links https://developer.wordpress.org/reference/hooks/pre_get_posts/#comment-2571
https://stackoverflow.com/questions/47869905/how-can-i-filter-records-in-custom-post-type-list-in-admin-based-on-user-id-that