Use sp_drv_unitext_locator_charindex which accesses the Transact-SQL function charindex.
sp_drv_charindex_unitextloc_in_locator search_locator, locator, start, position
search_locator – a unitext_locator that points to the literal to search for.
locator – a unitext_locator that references the text column to search from.
start – an integer specifying the position from which to begin searching. The first position is 1.
position – an integer specifying the starting position of the literal in the LOB column referenced by locator.
None.
