Searching text in datagridview column in vb.net

I have a datagridview with list of items in the column. I have a text box where i type a search string.

Currently i have implemented a method which is working in almost all scenarios except the following one
  Suppose a list contains a 24hrs S Creatinine and S creatinine and when i type a  creatinine
   it searches first occurance of the string and highlights it.

My code for the same is as below.

Private Sub TextBox9_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox9.TextChanged



        dgvOIList.ClearSelection()


        dgvOIList.Sort(dgvOIList.Columns("Oiname"), System.ComponentModel.ListSortDirection.Ascending)
        Dim rowindex As Long = GridRowLocator(dgvOIList, "Oiname", TextBox9.Text.ToUpper, "Text")
        If rowindex = -1 Then Exit Sub

        dgvOIList.Rows(rowindex).Selected = True
        dgvOIList.FirstDisplayedScrollingRowIndex = rowindex

        dgvOIList.CurrentCell = dgvOIList.Item("Oiname", CInt(rowindex))
        dgvOIList.CurrentCell.Selected = True


    End Sub




Public Function GridRowLocator(ByVal dtg As DataGridView, ByVal ColumnName As String, _
                                         ByVal ValueToSearch As String, ByVal strSearchType As String) As Long


        Dim CurrentRowIndex As Long = -1
        Try


            Select Case strSearchType.ToUpper

             

                Case "TEXT"

                    If dtg.Rows.Count > 0 Then
                        For i = 0 To dtg.Rows.Count - 1
                            If                  
                  dtg.Rows(i).Cells(ColumnName).Value.ToString.Contains(ValueToSearch.ToUpper) = True Then
                                CurrentRowIndex = dtg.Rows(i).Index
                                Exit For
                            End If
                        Next
                    End If


            End Select
        Catch ex As Exception
            MsgBox("Error: " & ex.Message, MsgBoxStyle.Information)
        End Try


        Return CurrentRowIndex

    End Function

My requirement is all the list items containing the search string should be grouped together one below another.  Can some expert pls advise on how to do this.