Queries :: Using A Function To Set SQL Criteria

I am using a function to set criteria in a an query. It reads the selected values from a combobox on a form and passes the appropriate value into the sql criteria.

E.g., the sql criteria is set to : like fnCountry()

And the function fnCountry() is something like;

If SelectedCountry = "All" Then
fnCountry = "*"
else fnCountry = SelectedCountry
end if

This works fine for a single selection (SelectedCountry = Africa) but doesn't work if I try to combine multiple selections into the criteria string.

E.g. SelectedCountry = Africa Or Italy

So the criteria would need to be
Like "Africa" Or like "Italy"

How else can i build this criteria with multiple values?