Do you mean the Holy Vindicator Prestige Class or the Holy Warrior Archetype, which you should already have in your classes?
Since you already are lvl 6, now starting to randomly dip clases doesn't seem ideal. If you now start with adding those fighter and cleric lvls, you won't reach your "Holy Warrior" till lvl 11.
Antipaladins rock. With a Conductive Weapon you can add your Touch of Corruption to your first attack. With a caster companion your auras will also be really potent.
Since you lose your favored class Bonus, you should have some reasons for multiclassing. What do you want from your Dips? A specific Cleric Domain? Full casting for a Prestige class? Why the Fighter lvls? Do you feel Feat starved?
Unless you exactly know, what you want from all those classes you should restrain from too much dipping.(Unless you do it exclusively for flavor, then just do it, but it won't be the mechanically best option.)
If you got some idea tell exactly, what you wanna get from those classes, then people can if it's optimal.
If you are unsatisfied with the Antipaladin you might also look at this http://www.d20pfsrd.com/basics-ability-scores/more-character-options/retrai ning
If there's something very specific you want that can be achieved with only a few levels, by all means multi-class. Otherwise, don't bother; the touch of corruption attack is absolutely amazing and it's not worth slowing down its progression significantly.
Do you have Necromatic Affinity?
If not there's this archetype here that will allow you to heal via negative energy in a one level dip. It's not done yet, but I have started and gotten most of the legwork done on my own guide to the class.