Modify widget in Entity Reference field select box?
Entityrefence 7.x-1.x-dev allows you to use results from a View in the select box, which will allow you to do what you need.


create/edit a view, add a new display of type "Entity Reference" to it, setting properly the fields you want to be shown;
edit the entityreference field, find "entity selection mode", set it to "views: filter by an entity reference view" then select the proper "view used to select the entities" option created on previous step.