The forum search is incessantly broken, so I'm not sure you're going to be able to accomplish that goal.
If unsure, just add your request to the end. If nothing else, more than one request for the same thing should increase its probability of being considered.
Instead of using Adobe's search engine, use Google.
Just enter the site you want to search followed by the search. Works well for most forums where the forum search engine is not great.
Here's how: Navigate over to google. Enter your search term as follows:
site:forums.adobe.com "Camera Raw" Features Requests
This says to search the site forums.adobe.com for the words Camera Raw (together in that order), and must also contain the words features and requests.
You can narrow the search further by adding more words that must be in the page, or you can exclude items by putting a minus sign in front. So if you got a bunch of hits with Canon in them and you were not looking for Canon, add -Canon to your search:
site:forums.adobe.com "Camera Raw" Features Requests -Canon