调用方法如下：

var query = db.T_Article.Where(t=>t.IsAudit);
query = Search(query, t=>new{t.Title, t.Content}, new[]{"key1", "key2"});

代码如下（记得using System.Linq.Expressions）

    IQueryable<MyTable> Search<MyTable, MyField>(IQueryable<MyTable> query, Expression<Func<MyTable, MyField>> arrField, string[] arrKeyword)
    {
        Expression rule = null;
        foreach (var strKey in arrKeyword)
        {
            if (strKey.Trim() == "") continue;
            foreach (var field in ((NewExpression)arrField.Body).Arguments)
            {
                var expr = Expression.Call(field, typeof(string).GetMethod("Contains"), Expression.Constant(strKey));
                if (rule == null)
                {
                    rule = expr;
                    continue;
                }
                rule = Expression.Or(rule, expr);
            }
        }
        if (rule == null) return query;
        return query.Where((Expression<Func<MyTable, bool>>)Expression.Lambda(rule, arrField.Parameters[0]));
    }