Full text indexing is one way to go. Another way would be to create a keywords table and have a productskeyword join table. You could have a trigger on insert/update to add to the 2 tables.
For example
Products
ItemID ItemDescription
1, 100% cotton short sleeve t-shirt
2, 50/50 cotton poly blend
Keywords
KeywordID, Keyword
1, Cotton
2, short
3, sleeve
4, t-shirt
5, shirt -- if you decide to do words with/without prefix/suffix/stems/plurals, etc
6, long
7, long sleeve -- if you allow phrases
8, blend
ItemKeywords
ItemID, KeywordID
1,1
1,2
1,3
1,4
1,5
2,1
2,8
Now, you can simply do your select with
JOIN ItemKeywords ik
ON ik.ItemID = products.ItemID
JOIN Keywords k
ON k.KeywordID = ik.KeywordID