Investor Warren Buffett believes that the economy and the U.S. job market will continue to improve, but slowly.

In an interview that aired Friday, Buffett said business has been creeping upward at his Berkshire Hathaway conglomerate.

"The economy is improving, not at a rapid clip, but this country has done well since 2008 — certainly compared to the rest of the world," Buffett said to CNBC.

Editor’s Note: Put the World’s Top Financial Minds to Work for You

Buffett thinks it would be extraordinary if the Federal Reserve were to expand its bond-buying program beyond the current $85 billion a month level. The Fed said Wednesday that it would consider buying more if the economy needs help.

Fed Chairman Ben Bernanke needs some help from elsewhere to get the economy moving faster, Buffett said. Bernanke has urged Congress to do more to stimulate hiring and growth.

On Saturday, Buffett will take questions in front of more than 30,000 people at Berkshire's annual meeting.

In a separate interview with the Fox Business Network on Friday, Buffett tried to reassure Berkshire shareholders that they shouldn't worry about his successor.

The 82-year-old billionaire said he isn't concerned about who will next lead four companies in which Berkshire invests nearly $50 billion, such as Coca-Cola, IBM, Wells Fargo and American Express.

"I don't know who's going to succeed the present CEOs there and in every case, each one of the four they have changed CEOs since we started buying the stock in certain cases more than once," Buffett said. "I never knew who they were going to be. I knew they'd pick good people."

Buffett said Berkshire's board spends more time discussion succession planning than any other topic. But Buffett has no plans to retire. He has said Berkshire's board has picked someone to succeed him as CEO if the need arises immediately, and it has two backup candidates. But Buffett won't publicly identify his successor, partly because he has said the candidates could change over time.

Currently, all of the CEO candidates on Berkshire's short list are men, but Buffett said that could change.

"Maybe 10 years or 15 years from now it will be a she. I hope it is," he said.

Berkshire plans to split Buffett's job into three parts when he no longer leads the company. The next CEO will run Berkshire, but two others hired by Buffett in recent years will oversee investment. Buffett wants his oldest son to succeed him as chairman.

Berkshire owns more than 80 subsidiaries, including railroad, clothing, furniture and jewelry firms. Its insurance and utility businesses typically account for more than half of the company's net income. The Omaha, Neb., company also has major investments.

Editor’s Note: Put the World’s Top Financial Minds to Work for You