Edit: Don't have data to test, but something like this should do it.

SELECT tn.ID,ca.Client,tn.TxDate,tn.GrossCost

FROM table_name tn

CROSS APPLY (

SELECT tn.Client AS Client

UNION ALL

SELECT 'LEN'

WHERE tn.Client = 'Dest'

UNION ALL

SELECT 'ghi'

WHERE tn.Client = 'Dest'

UNION ALL

SELECT 'tab'

WHERE tn.Client = 'Dest'

) AS ca