want to be able to multiselct in multiple columns, currently can the code only allows 1

How would I correct this code to be able to have it work for multiple columns?�*



Private Sub Worksheet_Change(ByVal Target As Range)


Dim Oldvalue As String
Dim Newvalue As String
Application.EnableEvents = True
On Error GoTo Exitsub
Const rngA = "U6:U468" Or "V6:V468"
If Not Intersect(Target, Target.Parent.Range(rngA)) Is Nothing Then
If Target.SpecialCells(xlCellTypeAllValidation) Is Nothing Then
GoTo Exitsub
Else: If Target.Value = "" Then GoTo Exitsub Else
Application.EnableEvents = False
Newvalue = Target.Value
Application.Undo
Oldvalue = Target.Value
If Oldvalue = "" Then
Target.Value = Newvalue
Else
If InStr(1, Oldvalue, Newvalue) = 0 Then
Target.Value = Oldvalue & vbNewLine & Newvalue
Else:
Target.Value = Oldvalue
End If
End If
End If
End If
Application.EnableEvents = True