I guess you need to use **hook_views_query_alter** and then you could add your **OR** condition.

    function hook_views_query_alter(ViewExecutable $view, QueryPluginBase $query) {
      if ($view->id() == 'machine_name_of_your_view' ) {
       //$query->where contains the filter conditions 
       //i.e. AND part of the query where you could add yours.
       print_r($query->where);die;
      }
    }

[more from drupal.org][1]


  [1]: https://api.drupal.org/api/drupal/core!modules!views!views.api.php/function/hook_views_query_alter/8.2.x