No, there no preposition in Czech there. English is irrelevant and so is German, Cantonese or Swahili, Czech does not care if any of these languages does or does not use a preposition in the ewuivalent of "hledat".
i see what you did there. JEHO is a strong version of HO. but JI does not have a sibling of that sort. JEJI does not exist. (and JEJÍ is a possessive, her/hers.) JI actually embodies the qualities of both HO and JEHO.