Search and Highlight

Hi,
I have this code and would like to modify little bit with your help. Here is what i want to do:
1)I would like to search each cell in every column in the entire worksheet. The code currently searches only in column A and i would like to expand it in the entire sheet.
2) I need only to search and highlight if it finds the list of words that i specified like the word "BT" or "BTG" But the problem with this code is that it finds and highlights any word that contain the words "BT" or "BTG". For instance, it finds like this word "BTGL" or "BTA" but i want only to find the words that i specify in my list. I would really appreciate if you can help me with this. Thank you so much.

Sub FindAndHighlight(SearchData As Variant, SearchRange As Range, HighlightColor As Long)

   Dim FirstAddress As String
   Dim SearchCell As Range
   Dim SrcWks As Worksheet

     Set SrcWks = Worksheets(SearchRange.Parent.Name)
     
     Set SearchCell = SearchRange.Find(What:=SearchData, After:=SearchRange.Cells(1, 1), _
                        LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByColumns, _
                        SearchDirection:=xlNext, MatchCase:=False)
                        
     If Not SearchCell Is Nothing Then
        FirstAddress = SearchCell.Address
          Do
              SearchCell.Cells.Interior.ColorIndex = HighlightColor
              
            Set SearchCell = SearchRange.FindNext(SearchCell)
          Loop While Not SearchCell Is Nothing And SearchCell.Address <> FirstAddress
     End If
          
End Sub

Sub HighlightRisk()
  
   Dim LastRow As Long
   Dim RiskCol As Variant
   Dim RiskRange As Range
   Dim StartRow As Long
     
    RiskCol = "A"
     StartRow = 1
      With Worksheets("Sheet1")
        LastRow = .Cells(.Rows.Count, RiskCol).End(xlUp).Row
        LastRow = IIf(LastRow < StartRow, StartRow, LastRow)
        Set RiskRange = .Range(.Cells(StartRow, RiskCol), .Cells(LastRow, RiskCol))
      End With
      
      FindAndHighlight "BT", RiskRange, 3      'Red
      FindAndHighlight "BTG", RiskRange, 5    'Blue
      FindAndHighlight "BTI", RiskRange, 4       'Green
      FindAndHighlight "BTP", RiskRange, 1
      FindAndHighlight "NT", RiskRange, 16
      FindAndHighlight "NTG", RiskRange, 2
      FindAndHighlight "NTI", RiskRange, 8
      FindAndHighlight "NTP", RiskRange, 9
      FindAndHighlight "PT", RiskRange, 10
      FindAndHighlight "RT", RiskRange, 11
      FindAndHighlight "SQE", RiskRange, 12
      FindAndHighlight "TR", RiskRange, 13
      FindAndHighlight "TRSYN", RiskRange, 14
      FindAndHighlight "TT", RiskRange, 15
End Sub