How to run entityfieldquery on all fields in node that reference users
Can you try rephrasing your question? It is not clear what you are trying to accomplish. Do you want to load all nodes that use the same field to reference a user? 

If so, you would use the fieldCondition() method. Something like


->fieldCondition('field_name', 'target_id', $uid)


See https://api.drupal.org/api/drupal/includes!entity.inc/function/EntityFieldQuery%3A%3AfieldCondition/7 for more information.