Here\'s what I would like to do:
Update You need two loops for what you want to do. This new subroutine works for any row. Just be careful of multiple matches because it will take only the last match:
Sub CopyCells()
Dim sh1 As Worksheet, sh2 As Worksheet
Dim j As Long, i As Long, lastrow1 As Long, lastrow2 As Long
Set sh1 = Worksheets("Worksheet A")
Set sh2 = Worksheets("Worksheet B")
lastrow1 = sh1.Cells(Rows.Count, "A").End(xlUp).Row
lastrow2 = sh2.Cells(Rows.Count, "A").End(xlUp).Row
For i = 2 To lastrow1
For j = 1 To lastrow2
If sh1.Cells(i, "H").Value = sh2.Cells(j, "E").Value And _
sh1.Cells(i, "J").Value = sh2.Cells(j, "H").Value And _
sh1.Cells(i, "K").Value = sh2.Cells(j, "I").Value Then
sh1.Cells(i, "L").Value = sh2.Cells(j, "O").Value
End If
Next j
Next i
End Sub