You need to have two separate conjunctions added to a single disjunction. Something like:
var conjunction1 = Restrictions.Conjunction();
conjunction1.Add(Restrictions.Eq("patientid", 101));
conjunction1.Add(Restrictions.Eq("PatientCaseId", 1316));
var conjunction2 = Restrictions.Conjunction();
conjunction2.Add(Restrictions.Eq("patientid", 105));
conjunction2.Add(Restrictions.Eq("Case_type", 1));
var orDisjunction = Restrictions.Disjunction();
orDisjunction.Add(conjunction1);
orDisjunction.Add(conjunction2);
return session.CreateCriteria(typeof(PatientDetailInformation))
.Add(orDisjunction)
.List<PatientDetailInformation>()
.ToList();
Hope it helps.