I'm going to make an assumption:
Your records look like this:
So a record might look like
"Journal of American Philatelists", "25-Dec-2002", "Hapenny 1892 Black, Borneo 1925 Black, Scams, Tongue Disease"
If you are entering data like this, and you have the choice to do it, you chose to do it wrong. If you get this data from another source, you need to write a parser before actually storing it.
In the ideal world, each entry should be a date, a name, and a SINGLE topic keyword. Makes the table deeper but narrower. If you do it that way, it suddenly makes sense to put an index (non-unique, of course) on the keyword field. Which will help your search performance tremendously.
OK, having now issued the appropriate advice on what it SHOULD look like, here is how to make it work with the run-together stuff.
When searching for the keywords, use the following...
... "WHERE [stKeyWords] LIKE ""*" & [stTargetedText] & "*"""
When you let the quotes get evaluated, the result would be
WHERE [stKeyWords] LIKE "*your-search-text*"