How To Create Combined Search Filters In Views?
The newest version of Views integrates this feature without the need for Views filter populate.  It's a filter called Combine fields filter.

To make use of it you first need to add all of the fields you want to filter on.  You may check Exclude from display if you want to search for it, but don't want to display it.

Once all of the fields are there, add a Combine fields filter, and choose to Expose it.  Choose Single field for the Filter type to Expose

This is a different approach than Views populate filter, but as this is integrated into Views I find it much more intuitive.