Display ‘username’ instead of ‘display name’ from selection

In the author box, when I type a name to search for an user in order to include that user to be an author, the selection is from ‘username’ field. How can I change that to ‘display name’ field?

Using ‘display name’ field is better since very often most websites user ’email address’ as username so that users do not have to type both username and email in registration process.