User usr = new User();
  usr.FirstName = "J%";
  usr.LastName = "Gore";
  IList<User> users = session.Find(usr) as IList<User>;

    public class Manager
    {
        public IList<T> GeneralFind<T>(T searchPattern)
        {
            ISession session = NHibernateHelper.GetCurrentSession();
            ICriteria criteria = session.CreateCriteria(typeof(T));

            // Reflect all properties to get search params
            PropertyInfo[] properties = searchPattern.GetType().GetProperties();
            foreach (PropertyInfo property in properties)
            {
                object value = property.GetValue(searchPattern, null);

                // Strings can use Like
                if (value.GetType() == typeof(string))
                {
                    string valueStr = value as string;
                    if (valueStr.IndexOf("%") >= 0)
                        criteria.Add(Expression.Like(property.Name, value));
                    else
                        criteria.Add(Expression.Eq(property.Name, value));
                }
                else
                    criteria.Add(Expression.Eq(property.Name, value));
            }

            return criteria.List<T>();
        }
    }

  //And to fetch data:
  User usr = new User();
  usr.FirstName = "J%";
  usr.LastName = "Gore";

  Manager mgr = new Manager();
  IList<User> users = mgr.GeneralFind<User>(usr);

ICriteria criteria = NHibernateSession.CreateCriteria(persitentType);
Example example = Example.Create(exampleInstance);