You don't need to change anything to achieve that, as the macro already looks for the column text in the subject

If InStr(1, .Subject, Arr(1, iRows)) > 0 Then
Arr(1, iRows) is the data from the Subject column of the worksheet. If you have 'testing' in The column, it will match with 'testing help' in the message subject. It will not however match with 'Testing help'. If the subject may have mixed case, change the line to

If InStr(1, LCase(.Subject), Arr(1, iRows)) > 0 Then
and ensure the worksheet column only has lower case entries.