Goddess lakshmi is considered wife of Lord vishnu and I have also checked verse in Sri suktam calling devi lakshmi wife of Lord vishnu but that could be later addition.so I want to know is goddess Lakshmi called wife of Lord vishnu in the original Rig Veda khillani Sri suktam?
Yes but in later verses :—optional to go through this link (https://en.m.wikipedia.org/wiki/Śrī_Sūkta)
Why i am saying this check it out verses which goddess lakshmi as lord vishnu's consort are not part of verses see these are those last verses :—
Invoke for me O Agni, that Goddess Lakshmi, who is ever unfailing, being blesses by whom I shall win wealth in plenty, cattle, servants, horses and men.
We commune ourselves with the Great Goddess, and meditate on the consort of Vishnu; may that Lakshmi direct us (to the Great Goal). Om May there be Peace, Peace, Peace.
While the sukta end with this verse:—
(13-14) Invoke for me, O Agni, Lakshmi who shines like gold, is brilliant like the sun, who is powerfully fragrant, who wields the rod of suzerainty, who is the form of supreme rulership, who is radiant with ornaments and is the goddess of wealth. Invoke for me O Agni, the Goddess Lakshmi who shines like gold, blooms like the moon, who is fresh with anointment (of fragrant scent), who is adorned with the lotuses (lifted up by celestial elephants in the act of worship), who is the presiding deity of nourishment, who is yellow in colour, and who wears garlands of lotuses.
So thirteen(13) and fourteen(14) are last verses after that they are later added which are not part of original sukta verses but later added it is upto your belief that you aknowledge these later verses or not if you have read upnishads there is a starting prayer which really from where it is taken do not exist like isha upnishad is chapter 40 of yajurveda but the starting prayer is not present in yajurveda so it is upto you to aknowledge that last prayer of sri sukta as authentic or in-authentic now its about belief but the last verses are not part of sukta.
(MY INTENTION IS NOT TO HURT ANYBODY FEELINGS THAT 'S WHY I LEAVE THE ANSWER AS SUBJECT TO PERSONAL BELIEF.)