This question is an exact duplicate of:
I have an Album content type with some fields, including a contact field, which is an Entity reference field (taxonomy).
My contact taxonomy field has 3 text fields. I want to be able to add a contact to my Album content type with the autocomplete widget, but I want this autocomplete field to search from all of my 3 contact fields, not only the title field (default behavior).
I have also tried to use the functionality Views: Filter by an entity reference view that comes with the Entity Reference module (Drupal 8 core) to search on more fields, as seen on https://drupal.stackexchange.com/a/125046/57071, but after creating my view, my autocomplete field return me a
500 fatal error (through AJAX) because of missing fields/relations.
I'm working with Drupal 8.0.2.