Then just use the Right command - you can check for beginning or ending:
If Left(vData(j), 1) = "K" Or Right(vData(j), 1) = "K"
-------------------------- Code added
Dim j As Integer
Dim sData As String
Dim vData As Variant
'Test data
sData = "This is a test of the K1212121|0 string that has another K334343 value."
'Get the array of space delimited words into an array - this assumes data is split by spaces!
vData = Split(sData, " "
'Check for more than one 'K' value - this assumes your K values start the word
For j = 0 To UBound(vData)
If Left(vData(j), 1) = "K" Or Right(vData(j), 1) = "K" Then
'Here is your value vData(j)
sData = vData(j)
End If
Next j