client：意为客户，这个只表示银行，广告或律师之类的客户，和另两个很好区分。 对于customer和consumer，我上marketing的课的时候区分过这两个定义。 customer behavior：a broad term that covers individual consumers who buy goods and services for their own use and organizational buyers who purchase business products. consumer behavior：the process ...
Client's => the opinion of one of your clients. Clients' => the opinion of several of your clients. 3 is incorrect - you must include the possessive apostrophe.
Could you perhaps give the whole sentence? My immediate thought is that having both "our client" and "we" in the subject is somewhat redundant. If you're issuing an invitation on your client's behalf, then it seems obvious that you're participating somehow, for instance.
