This is a screenshot of the worksheet with a brief explanation below.

You can download the file in Office 2003 format by clicking this link.

The search text is typed into C1.

This triggers a search for that word in column A by the formula in column C e.g.

=ISNUMBER(SEARCH($C$1,A3))

 

The cells in column A are highlighted using conditional formatting.

This is based on the result in column C

 

Or you could put the search formula directly into the conditional formatting