<?xml version="1.0" encoding="utf-8"?>
<NewDataSet>
  <tab_Daten>
    <GUID>802bbd17-700d-4132-b6a5-570e6f94a203</GUID>
    <LfdNr>1777783</LfdNr>
    <Region> 1777783</Region>
    <StO> 1777783</StO>
    <Abteilung> 1777783</Abteilung>
    <Projekt> 1777783</Projekt>
    <Bearbeiter> 1777783</Bearbeiter>
    <AngebotsNr> 1777783</AngebotsNr>
    <AuftragsNr> 1777783</AuftragsNr>
    <Kunde> 1777783</Kunde>
    <Straße> 1777783</Straße>
    <PLZ> 1777783</PLZ>
    <Ort> 1777783</Ort>
    <Aspar> 1777783</Aspar>
    <Telefon> 1777783</Telefon>
    <KDAZ> 1777783</KDAZ>
    <Baustelle> 1777783</Baustelle>
    <Angebotsvolumen> 1777783</Angebotsvolumen>
    <Auftragsvolumen> 1777783</Auftragsvolumen>
  </tab_Daten>
.....
....

Dim MyXmlDoc As New XmlDocument
MyXmlDoc.Load("c:\test.xml")
 
Dim lc As String = "'abcdefghijklmnopqrstuvwxyzüöä'"
Dim uc As String = lc.ToUpper()
Dim suchtext As String = "meinAuto"
Dim My_Arguments_A As String = "'" & suchetext.ToUpper() & "'"
 
Dim My_Search As String = "descendant::tab_Daten[ (translate(*," & lc & "," & _
  uc & ") = " & My_Arguments_A & ") or (translate(Projekt," & lc & "," & uc & _
  ") = " & My_Arguments_A & ")  ]"
 
Dim ErgebnisListe As XmlNodeList = Nothing
ErgebnisListe = MyXmlDoc.SelectNodes(My_Search)
msgbox  ErgebnisListe.count()

Dim My_Search As String = "descendant::tab_Daten[ (translate(Region," & lc & _
  "," & uc & ") = " & My_Arguments_A & ") or (translate(Projekt," & lc & "," & _
  uc & ") = " & My_Arguments_A & ")  ]"