Tell them that you want to help in the areas that need improvement. Don't be pushy. Plenty of clients will need and want the help immediately. For others, it may take some time for them to see you as their financial advisor or even realize that they need your help. Eventually, they will do what you've advised they need to do, and good marketing will make you the obvious choice as their planer, advisor or insurance broker when they are ready.
Seminars also work great with existing clients.
They are a non-threatening environment where clients can learn, from someone they already trust, about subjects they don't have the time or expertise to fully understand. When a client discovers the many ways that you can now assist them, you are likely to be their first call after the seminar. In fact, not only will your clients call, their friends are likely to call you as well. When the topics of financial advisors come up, you can be sure that you will be mentioned as the credible CPA who also provides financial planning. Several CPA's have cited an increase in client referrals when they began their PFP practices.