How to get a field in a exposed filter criteria as an autocomplete?
You can use Views Autocomplete Filter for getting autocomplete exposed filter in views. Module page says :

Add autocomplete functionality to the views filter text fields.

 - It works for node titles or cck text fields.
 - The autocomplete results are actually the view results, so they are view related.


But the field which you will expose &amp; use autocomplete should be in the views result fields as well.