as per modification time stamp

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Cells.Count > 1 Then Exit Sub
If Not Intersect(Target, Range("B4:B15")) Is Nothing Then
With Target(1, 16)
.Value = Time
.EntireColumn.AutoFit
End With
End If
End Sub

what above macro doing is if i enter values to b4 to b16 any cells that cells data entering time add to column Q4 to Q16. my requirement is i want to add another 2 columns to this code as per bellow. pld help me to edit this macro..

if number enter values to B4:B16 time should add to Q4:Q16
if number enter values to C4:C16 time should add to R4:R16
if number enter values to D4:D16 time should add to S4:S16