Compare String Of Words To Cell Content

I need to compare a list of keywords (stored in a string variable) with the content of a cell in order to see if any of the keywords do appear in the cell. I have to work with many such lists which can grow over time. What I'm doing is using InStr(cell with content, keyword) for each keyword. My goal is to have a macro which can automatically create the long formula from any list. My actual problem is that the formula I've build and stored acts more like a string. I'd like it to say either true or false. Anyway, here's a sample of what I came up with so far.

Sub build_formula()
Dim i As Integer, j As Integer, m(20) As Integer, n As Integer, z As Integer
Dim List As String, f(2) As String, s(20) As String, sp As String, Source As String
Dim Formula As Variant
List = "black, blue, green, red, yellow, white, z"
Source = Cells(3, 1).Value
z = InStr(1, List, "z")
i = 1
n = 1
Do
i = InStr(i + 1, List, ",")
m(n) = i ..........................