filter expression for search string

[john83]

whats a good filter expression for one up to 3 keywords.

if one keyword, it will be
NAME = '*keyword1*'

if 2 keyword, it will be
NAME = '*keyword1*' OR NAME = '*keyword2*'

if 3 keyword, it will be
NAME = '*keyword1*' OR NAME = '*keyword2*' OR NAME = '*keyword3*'

problem is how do i know if its 1 or 2 or 3 keyword entered in a search string