This thread was very helpful for us to accomplish the same thing. We wanted to expand the keyword search to search more parameters. Some OOTB and some customer meta data attributes.
We did add 'description' and our own attribute to the file Guilherme Dreossi posted but still had some difficulties getting the additional attributes to function as expected in the keyword search textbox. For example when we added description to the list, notice the space after the comma and before the word description.
keywordSearch.wt.doc.WTDocument=number,name, description
We had sent out some emails trying to see who else might have a quick solution to our problem because based on this thread we thought we were really close but discounted the space as a potential issue.
Another one of PTC's resellers, BWIR, responded to our inquiry and offered two additional things to try. These worked for us.
1. Remove the space after the comma and before the "D" in description
2. Also add description and our other attributes we wanted the keyword search to evaluate in the 'keywordSearch.wt.fc.Persistable' property list. Again with no spaces between the commas and the attribute names.
We let our normal backup (shutdown/restart) process at night run and the next morning our keyword searching was searching more than just the name and number fields. This greatly streamlined the searching for our downstream users of the engineering data.
We implemented both items #1 and #2 above at the same time so I do not know which one really solved our problem.
It took us a while to find this post but was what we were looking for.