This sort of thing :

Sub change_rect()
Dim osld As Slide
Dim strText As String
For Each osld In ActivePresentation.Slides
If osld.Shapes.HasTitle Then
strText = osld.Shapes.Title.TextFrame.TextRange.Text
If InStr(UCase(strText), "JOHN") > 0 Then
On Error Resume Next
osld.Shapes("Rectangle 4").Fill.ForeColor.RGB = vbRed
End If
End If
Next osld
End Sub