Hi :)
The roadmap for the Views module include the possibility of having alternatives in the list of filters - in effect, an OR operator.
However, this functionality is not yet present (and won't be for 2.0), and so some time ago I wrote the Views Or module which adds this functionality : http://drupal.org/project/views_or
As per this thread http://drupal.org/node/291660 , this module will be superseded when the functionality gets implemented into Views proper. In the mean time, it's a space where we can experiment with the functionality, and hash out problems and bugs before it gets implemented into Views.
So if you are maintaining a Views filter, and would like/have the time to help, it would really helpful if you could try your filter with the Views Or module and see if it generates the expected results !!!
Thanks :)
Anselm