The messaging center allows you to search conversations for any word or phrase.
In the messaging center use the search box from the top left.
Enter any phrase and click the magnifying glass icon to run a search.
The contact list on the left will now show the relevant contacts and how many matching messages were found for each one.
To reset a the search click the “x” in the search box.
You can also use the time picker in the top right to narrow down a time range.