Another feature growing in popularity is telephone access to financial advisors. This year, 53 percent are providing this service to participants; that's up substantially from only 35 percent in 2014. 

About half (49 percent) of employers are offering third-party investment advice; that's grown from 44 percent last year. 

And 47 percent are offering managed accounts this year, up from 39 percent in 2014. 

"Employers' focus on financial wellness has been steadily picking up steam in recent years," said Rob Austin, director of retirement research at Aon Hewitt. "This year, even more organizations will address this topic head-on and help workers think beyond just saving enough for retirement and consider all aspects of their financial health."  

In some cases, that means companies are now offering help on how to save for life events such as a home purchase or college.

A Certified Financial Planner Board of Standards study last year found that financial stress is negatively impacting work performance. About 20 percent of employees went so far as to admit they skipped work to deal with financial problems.

Financial education aside, companies also are cutting costs connected with DC plans, Aon Hewitt said.

Sponsors are using their scale and purchasing power to win reduced expenses and try to improve plan returns. More than a third (34 percent) recently changed fund lineups to cut costs, while in 2014 only 27 percent did so.

Moreover, almost double the number of employers have switched this year (30 percent compared with 16 percent in 2014) from mutual funds to institutional funds or separately managed accounts. 

"Employers understand that small plan fees can add up and ultimately make a big impact on workers' retirement savings," Austin said. "To help workers maximize their retirement dollars, employers are scrutinizing each fund in the plan to determine if the associated fees are reasonable."

The survey results are based on the responses of nearly 250 U.S. employers representing about 6 million employees.